Scientists have long known that drinking alcohol impacts women and men in different ways. Women metabolize alcohol differently than men, and studies have linked drinking to an increased risk of some cancers, including breast cancer. But for breast cancer survivors, there’s another question: Should they reduce the amount they drink, or stop drinking entirely?
A new study, conducted by researchers at Kaiser Permanente’s Northern California Division of Research and published in the journal Cancer, offers good news for breast cancer survivors who enjoy the occasional glass of wine. In what the researchers describe as the largest prospective study to look at short-term alcohol use after a breast cancer diagnosis, they found that drinking alcohol is not associated with an increased risk of breast cancer recurrence or dying from the disease. They also found that moderate drinking may even improve health outcomes in obese women.
“We know that women who drink alcohol are at increased risk of developing breast cancer and that the risk increases as alcohol use increases,” lead author Marilyn Kwan, PhD, a research scientist with Kaiser Permanente, said in a statement. “For this reason, we thought that drinking alcohol after a breast cancer diagnosis could increase the risk of a cancer recurrence. But our study found that, overall, drinking alcohol after a breast cancer diagnosis does not impact a patient’s prognosis.”
The Link Between Alcohol and Breast Cancer Recurrence
The researchers collected data from the Pathways Study, which followed more than 4,500 women diagnosed with invasive breast cancer at Kaiser Permanente Northern California from 2005 to 2013. It is one of the largest U.S. studies to follow breast cancer survivors to track the relationship between lifestyle changes and outcomes.
More than 3,600 of the women filled out a health questionnaire about their alcohol consumption when they were diagnosed and again six months later. Over the following 11 years, 524 of the women had a breast cancer recurrence and 834 women died—369 from breast cancer, 314 from cardiovascular disease and 151 from other health problems. By comparing the women’s drinking habits and health outcomes over that time period, the researchers did not find a link between alcohol consumption and cancer recurrence or overall mortality. The type of alcohol consumed generally did not impact the results, though beer consumed after diagnosis was associated with a higher risk of death from breast cancer.
Until this study, the evidence regarding drinking after a breast cancer diagnosis was mixed. The authors write that “no specific guideline exists for cancer survivors” about how much alcohol is safe. Given alcohol’s established ties to breast cancer, patients are often advised to reduce their alcohol intake. The new study provides crucial insight into the effects of consumption in the six months following diagnosis, the time period when many women consider lifestyle changes to reduce their risk of recurrence and mortality.
Do the Potential Benefits of Alcohol Outweigh Breast Cancer Risk?
In obese women, consuming more than two alcohol drinks per week was associated with a lower risk of death from any cause—especially cardiovascular disease, a frequent cause of death in breast cancer survivors. The study did not find a similar association for non-obese drinkers, who had a possibly greater, but not statistically significant, risk of recurrence than obese women.
The researchers speculate that their results may be due to the fact that the obese women in the study who drank regularly were more educated and physically active than those who didn’t. They also note alcohol’s ability to improve insulin sensitivity and reduce levels of insulin-like growth factor 1, which could decrease the risk of type 2 diabetes, cardiovascular disease and cancer. Since the amount of alcohol distributed throughout the body can decrease with higher body mass index, they also speculate that some of alcohol’s adverse health effects could have been reduced in obese women.
The study does have limitations. It relied on self-reported drinking habits, which means women may have underreported how much they drank. The study controlled for many factors—including menopausal status, race, education, socioeconomic status, physical activity, smoking status, obesity and more—but the results could have been influenced by confounding variables.
Though the research is encouraging, the authors call for “other large prospective studies of breast cancer survivors with detailed exposure assessment and focus on body size.”
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